<!DOCTYPE html>
<html>
<head>
	<title>typeof</title>
</head>
<body>
	<h2>typeof对数组返回object,因为数组属于对象</h2>
	<h2>未初始化的变量返回undefined</h2>
	<p id="demo"></p>
	<script>
		var cars;
		document.getElementById("demo").innerHTML = 
		typeof 0 + "<br>" +
		typeof "a" + "<br>" +
		typeof "3.14" + "<br>" +
		typeof "bcd" + "<br>" +
		typeof cars;
	</script>

</body>
</html>